Projection imaging scanners are well established tools for bar code data entry in retailing and other industries. Some projection imaging scanners use laser technology to read bar codes. A laser projection imaging scanner generally uses a rotating polygon to scan a laser beam across an array of stationary mirrors and project a complex pattern of scan lines out into space in front of the scanner housing. This enables omnidirectional scanning of bar codes presented to the scanner or swiped across the face of the scanner. An example of this type of scanner is the LS-9100 available from Symbol Technologies, Inc.
A conventional projection imaging scanner generally works well on universal product code (“UPC”) bar codes and reduced space symbology (“RSS”) bar codes. However, such a projection imaging scanner does not perform well on some non-UPC bar codes (e.g., Code 39 and Code 128, and two-dimensional bar codes). An area scanners is therefore required to read such bar codes. Such an area scanner generally requires a specialized camera connected to computer which processes a received image of the bar code to identify and decode the bar code.
A bar code placed on a glossy material also cause performance problems for projection imaging scanners. Such a specular reflection, or glare where a light source reflects off a surface and into the optics of the scanner, often causes difficulty when reading such bar codes. Specular dead zones may obscure the bar code and prevent the image scanner from reading the bar code on its first attempt.